By default, a WebBrowser control is hosted. Script-accessible
properties (left, top, width, height, offsetLeft, offsetTop,
offsetWidth, offsetHeight, clientLeft, clientTop, clientWidth,
clientHeight, pixelLeft, pixelTop, pixelWidth, pixelHeight,
posLeft, posTop, posWidth, and posHeight) hold their proper values.
The source document can be in any format as long as it is
HTML-compatible. For example, XML (with or without XSL applied) can
be used because the WebBrowser control transforms it to HTML.

When no WebBrowser control is hosted, script-accessible dynamic,
geometric properties are always zero.